For starters, just listening in mono and stereo should tell you if there's any notable difference.
Some labels used to reissue old recordings by playing mono tapes in stereo (Atco on LP, London on CD) and those sometimes had a bit of stereo spread (or the result of dirty playback heads or unbalanced channels) and sounded pretty slushy in mono.
Mike -- mrichter@xxxxxxx http://www.mrichter.com/